Radial roller bearings that employ cylindrical rollers as rolling bodies have greater load capacity and higher stiffness than radial ball bearings. Therefore, the radial roller bearings are excellent for use in rotary support parts to which large loads are applied. A retainer that rollably retains rollers is usually composed of press-molded items obtained by press-machining of metal plates. The material of a metal plate that is employed is, for example, SPCC (JIS-standard cold rolled sheet steel), SPHC (JIS-standard hot rolled sheet steel), SPB1 or SPB2 (BAS-standard (Japan Bearing Industry Association-standard) low carbon sheet steel), or the like. Such radial roller bearings require high dimensional precision.
Inventions have been disclosed that suppress falls in dimensional precision that arise in various processes, through structurally devising retainers (for example, see Patent Document 1).
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2005-147364